The present disclosure relates generally to the field of downhole tools and, more particularly, to systems and methods for calibrating calipers on a downhole tool.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present techniques, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions.
A variety of downhole tools may be used to determine the properties of a geological formation surrounding a well. Some downhole tools may include calipers, which provide a measurement of the diameter of the wellbore at various depths. Caliper measurements are used in a variety of operations, including drilling, cementing, and evaluation of the geological formation. During drilling, for example, the caliper data can be used to monitor the wellbore condition (e.g., identifying possible wellbore washout and/or impending wellbore instability), thus allowing the driller to take remedial action. During well completion, the caliper data can be used to accurately evaluate the volume of cement to fill the casing annulus, as well as aiding in the selection of casing points. A reliable caliper may also be useful during logging to adjust formation evaluation measurements for wellbore size and to evaluate the quality of other logging while drilling (LWD) logs. The caliper measurements can also be used to plan services, such as dip meters or formation testers, that may be affected by unfavorable wellbore conditions.
A variety of tools have been developed to accurately calibrate calipers before the downhole tool enters the wellbore. The accuracy of the calibration directly affects the quality of the measurements received from the calipers. For example, an improperly calibrated caliper may return inaccurate data of the wellbore and create challenges for operators during and after drilling operations. In some cases, calipers are calibrated using a calibration tool with a known inner diameter. Such existing calibration tools are now known to have certain drawbacks. For example, existing calibration tools are often subject to gravitational effects that can hinder an accurate centralization of the calibration ring, thereby affecting the accuracy of the calibration may be compromised. It is now recognized that there is a need for more accurate tools for calibrating the calipers on downhole tools.